Introduction/Background Brachytherapy boost plays a fundamental role in the therapeutic approach of patients with locally advanced cervical carcinoma, As there is no consensus on fractionation scheme for high dose rate brachytherapy treatment. The aim of our study was to report the oncological and toxicity results of two fractionation schemes

Methodology This is a retrospective study performed in a Department of radiotherapy at EHSO Emir Abdelkader in Oran - Algeria, including 149 patients treated between January 2014 and December 2019.

All patients received concomitant chemo radiotherapy at a dose of 46 Gy, followed by HDR uterovaginal brachytherapy with two different fractionations: 19.5Gy in 03 fractions (group1), and the 25Gy in 5 fractions (group2).

Results The 6.5Gyx3 regimen was used in 95 patients (64%), and the 5GyX5 regimen was used in 54 patients (36%).

The median follow-up was 41.72 months, the median EQD2 (α/β=10) of D90 HR-CTV was 77.52 Gy for group 1 and 77.85 Gy for group 2. The mean EQD2 (α/β=3) of D2cc of the bladder in group 1 and 2 was 74.84 Gy and 81.6 Gy (p=0.000), and the mean EQD2 (α/β=3) of D2cc of the rectum in group 1 and 2 was 68.52Gy and 68.86 Gy respectively (p=0.123). The 5-year recurrence-free survival for group 1 was 87.9±3.7% and 93.3±3.7% for group 2 (p=0.377), while the 5-year overall survival for group 1 was 76.8±4.7% and 74.6±9% for group 2 (p=0.563), with a non-significant difference between the 2 groups. Grade 3 urinary toxicity for group 1 and 2 was 12.1%/16.1% (p=0.096), and 7.9%/12.5% for grade 3 digestive toxicity (p=0.776).

Conclusion The two irradiation regimens used in HDR uterovaginal brachytherapy in 3 or 5 fractions give similar oncological results with a comparable late toxicity.

Disclosures HR CTV= high-risk clinical target volume

EQD2= Equivalent dose in 2Gy fractions